UTM coordinates format fix #9286

Merged

root merged 3 commits from utm-coord-format-fix into master

2024-09-14 17:53:06 +00:00

strump commented

2024-09-14 10:49:05 +00:00

Member

Closes #8593

In old UTM format zone letter could be either N for Northern Hemisphere or S for Southern. This information is enough to convert UTM format back to latitude and longitude.

But most geospatial applications use full zone letter instead. Updated UTM format to generate valid zone letter (the same way as we generate it for MGRS format).

TODO: Implement Universal Polar Stereographic (UPS) coordinate system for areas with lat < -80 and lat >= 84. See code for reference.

Closes #8593 ![Old-new-UTM-format](https://github.com/user-attachments/assets/be538f06-6ab7-402f-a574-086d5c8b3d17) In old UTM format zone letter could be either `N` for Northern Hemisphere or `S` for Southern. This information is enough to convert UTM format back to latitude and longitude. But most geospatial applications use full zone letter instead. Updated UTM format to generate valid zone letter (the same way as we generate it for MGRS format). TODO: Implement Universal Polar Stereographic (UPS) coordinate system for areas with lat < -80 and lat >= 84. See [code](https://github.com/mrJean1/PyGeodesy/blob/master/pygeodesy/ups.py) for reference.

vng (Migrated from github.com) reviewed 2024-09-14 13:44:31 +00:00

platform/utm_mgrs_utils.cpp

vng (Migrated from github.com) commented

2024-09-14 13:29:32 +00:00

nit: if (!maybeZoneLetter)

vng (Migrated from github.com) commented

2024-09-14 13:41:37 +00:00

So we return just anything that is not even initialized?
Probably, there is no problem here because I see:

  if (lat <= -80 || lat > 84)
    return {}; // Latitude limit exceeded.

everywhere in code.

I don't know if it is ok to have an invalid UTM for say (-88, 0), but this link gives a correct value (Z) for lat=-88
https://www.latlong.net/lat-long-utm.html

So we return just _anything_ that is not even initialized? Probably, there is no problem here because I see: ``` if (lat <= -80 || lat > 84) return {}; // Latitude limit exceeded. ``` everywhere in code. I don't know if it is ok to have an invalid UTM for say (-88, 0), but this link gives a correct value (Z) for lat=-88 https://www.latlong.net/lat-long-utm.html

strump reviewed 2024-09-14 15:03:15 +00:00

platform/utm_mgrs_utils.cpp

strump commented

2024-09-14 15:03:15 +00:00

Author

Member

UTM coordinates near the North and South poles are calculated with completely different formulas. For that purpose Z zone letter was introduced. We doesn’t support it for the moment, because those areas are not very popular. Let me update the code to cover latitude values outside of [-80, 84) range

UTM coordinates near the North and South poles are calculated with completely different formulas. For that purpose `Z` zone letter was introduced. We doesn’t support it for the moment, because those areas are not very popular. Let me update the code to cover latitude values outside of `[-80, 84)` range